Emulsion for damping materials and chipping-resistant materials

ABSTRACT

The present invention provides an emulsion composition for vibration damping materials which is capable of giving water-based vibration damping materials exhibiting very satisfactory thermal drying characteristics and vibration damping properties through improved dispersibility and stability and an emulsion composition for chipping-resistant materials which is capable of giving water-based chipping-resistant materials exhibiting satisfactory thermal drying characteristics and chipping-resistant properties. It also is directed to an emulsion composition for vibration damping materials which comprises an emulsion obtained by polymerizing a monomer composition containing an unsaturated carboxylic acid monomer as an essential component and a crosslinking agent. It further is directed to an emulsion composition for vibration damping materials or chipping-resistant materials which comprises an emulsion obtained by polymerizing a monomer composition containing an unsaturated monomer having two or more functional groups as an essential component.

FIELD OF THE INVENTION

The present invention relates to an emulsion composition for vibrationdamping materials and an emulsion for chipping-resistant materials. Moreparticularly, the present invention relates to an emulsion compositionfor vibration damping materials which can be used with advantage as aningredient in damper formulations (vibration damping formulations) andan emulsion composition for chipping-resistant materials which can beused with advantage as an ingredient in chipping-resistant formulations.

DESCRIPTION OF THE RELATED ART

Vibration damping materials are used to prevent vibration and noise ofvarious structures to insure sustained quietude and have been used notonly beneath the cabin floors of road vehicles but also applied torolling stock, ships, aircraft, electric machines, buildings, andconstruction machines, among other uses. As such vibration dampingmaterials, an inorganic powder-containing asphalt sheet has beeninstalled under automotive cabin flooring, for instance, but since thesheet must be secured in position by thermal fusion, improvements inworkability and other parameters are needed and studies are underway onvarious damper compositions and polymers for the formation of vibrationdamping materials.

Japanese Kokai Publication Hei-9-104842 discloses a water-basedvibration damper paint composition comprising at least one vehicleselected from the group consisting of synthetic resin emulsions andasphalt emulsions, an inorganic filler, and a synthetic resin powder ina certain ratio.

Japanese Kokai Publication Hei-11-29737 discloses a copolymer latex forwater-based paints which is obtainable by copolymerizing (a) analiphatic conjugated diene monomer, (b) an ethylenically unsaturatedcarboxylic acid monomer, and (c) a monomer other than theabove-mentioned monomers in a certain weight ratio in the presence ofα-methylstyrene dimer and having certain specified loss factor (tan δ)and toluene-insoluble fraction values.

Japanese Kokai Publication 2000-178497 discloses a copolymer latex forchipping-resistant paint which is obtainable by emulsion-polymerizing amonomer mixture comprising a conjugated diene monomer (a), anethylenically unsaturated carboxylic acid amide monomer (b), anethylenically unsaturated carboxylic acid monomer (c) and a monomerother than the above-mentioned ethylenically unsaturated monomers (d) ina certain weight ratio in the presence of an inorganic persulfatepolymerization initiator. Further, Japanese Kokai Publication2000-178498 discloses a copolymer latex for vibration damping materialswhich is obtainable by emulsion-polymerizing a conjugated diene monomer(a), an epoxy group-containing ethylenically unsaturated monomer (b), anethylenically unsaturated carboxylic acid alkyl ester monomer (c), andan ethylenically unsaturated monomer other than said (b) and (c)monomers (d) in a certain weight ratio. In addition, Japanese KokaiPublication 2000-178499 discloses a copolymer latex for vibrationdamping materials which is obtainable by emulsion-polymerizing a monomercomposition comprising a conjugated diene monomer (a), an epoxygroup-containing ethylenically unsaturated monomer (b), an ethylenicallyunsaturated carboxylic amide monomer (c), and an ethylenicallyunsaturated monomer other than said (b) and (c) monomers (d) in acertain weight ratio.

By any of these technologies, however, it is impossible to obtain avibration damping material which satisfies both thermal dryingcharacteristics and vibration damping properties sufficiently. Thus,when a synthetic resin emulsion or an asphalt emulsion is used and acoating film is formed by thermal drying, blisters tend to form as thevaporized moisture in the undried interior of the coating is forced outthrough the dried surface so that it is necessary to provide somemeasure for improving the thermal drying characteristics. When acopolymer latex comprising a conjugated diene monomer and other monomersis used, the conjugated diene monomer unit is not so contributory to theexpression of vibration damping properties so that there is room for acontrivance to reconcile satisfactory thermal drying characteristics andsatisfactory vibration damping properties.

SUMMARY OF THE INVENTION

Developed in the light of the above state of the art, the presentinvention has for its object to provide an emulsion composition forvibration damping materials which is capable of giving water-basedvibration damping materials exhibiting very satisfactory thermal dryingcharacteristics and vibration damping properties through improveddispersibility and stability and an emulsion composition forchipping-resistant materials which is capable of giving water-basedchipping-resistant materials exhibiting satisfactory thermal dryingcharacteristics and chipping-resistant properties.

The inventors of the present invention performed an exploratoryassessment of various raw materials to be used in many different damperformulations and had their attention directed first to the fact thatemulsions giving water-based vibration damping materials are superior inworkability and other respects. They discovered that not only thermaldrying characteristics but also vibration damping properties can beimproved by using an emulsion obtained by polymerizing a monomercomposition comprising an unsaturated carboxylic acid monomer as anessential component in combination with a crosslinking agent which iscapable of effecting interparticle crosslinking of the emulsion. Theyfurther found that by using an unsaturated monomer having two or morefunctional groups as an essential component of an emulsion-formingmonomer composition to give an internally crosslinked emulsion,improvements can be obtained not only in thermal drying characteristicsbut also in vibration damping properties of the emulsion. It was alsodiscovered that said interparticle crosslinking optimizes the emulsioncomposition for vibration damping materials and that said internalcrosslinking renders the emulsion suitable not only for vibrationdamping materials but also for chipping-resistant materials. Theyaccordingly conceived of the possibility of accomplishing the aboveobject in a neat way. Thus, in the vibration damping material formedfrom a damper formulation containing the emulsion composition forvibration damping materials of the present invention, improvements inthe prevention of vibrations and noise of various structures andconsequent maintenance of quietude are attained through theinterparticle crosslinking and internal crosslinking of the emulsion asmentioned above, and this effect seems to be derived from, inter alia,the constitution of a vibration damping material formed from saidemulsion, which is preferable as the emulsion composition for vibrationdamping materials, or the constitution of a chipping-resistant materialformed from said emulsion, which is preferable as the emulsioncomposition for chipping-resistant materials. It was further found thatwhen the glass transition temperature (Tg) of the emulsion is controlledwithin a certain range and/or the emulsion is formed from a monomercomposition containing an ethylenically unsaturated carboxylic acidmonomer and at least one other ethylenically unsaturated monomer in acertain mass ratio, very satisfactory thermal drying characteristics andvibration damping properties can be imparted to water-based vibrationdamping materials with improved reproducibility or very satisfactorythermal drying characteristics and chipping-resistant properties can beimparted to water-based chipping-resistant materials. The inventorsaccordingly have developed the present invention.

As further findings, it was discovered that when a metal oxide isincluded in a damper formulation or a chipping-resistant formulation,there can be obtained a water-based vibration damping material capableof expressing good thermal drying characteristics and vibration dampingproperties or a water-based chipping-resistant material expressing goodthermal drying characteristics and chipping-resistant properties. In wasalso discovered that as said metal oxide, a polyvalent metal oxide ispreferred, with zinc oxide or zirconium oxide being particularlypreferred.

The present invention, therefore, is directed to an emulsion compositionfor vibration damping materials which comprises an emulsion obtained bypolymerizing a monomer composition containing an unsaturated carboxylicacid monomer as an essential component and a crosslinking agent.

The present invention is further directed to an emulsion composition forvibration damping materials or chipping-resistant materials whichcomprises an emulsion obtained by polymerizing a monomer compositioncontaining an unsaturated monomer having two or more functional groupsas an essential component.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is now described in detail. The emulsioncomposition for vibration damping materials of the present invention canbe provided in a form (1) comprising an emulsion obtained bypolymerizing a monomer composition containing an unsaturated carboxylicacid monomer as an essential component and a crosslinking agent or aform (2) comprising an emulsion obtained by polymerizing a monomercomposition containing an unsaturated monomer having two or morefunctional groups as an essential component. These forms may be used ina suitable combination.

In the above emulsion composition for vibration damping materials (1),the inclusion of a crosslinking agent together with the emulsion asanother essential component leads to improvements in the thermal dryingcharacteristics of the emulsion composition for vibration dampingmaterials and in the vibration damping properties of the vibrationdamping material formed from a damper formulation containing suchemulsion composition for vibration damping materials as an essentialingredient.

The crosslinking agent mentioned above may be any compound that iscapable of reacting with two or more carboxyl groups and may be a singlecompound or a combination of two or more different compounds. Thepreferred crosslinking agent is at least one member selected from thegroup consisting of metal oxides, isocyanate compounds, blockedisocyanate compounds, melamine compounds, epoxy compounds, oxazolinecompounds and vinyl ether compounds. Among these, metal oxides areparticularly preferred and polyvalent metal oxides are most preferred.

As the polyvalent metal oxides referred to above, the preferred speciesare zinc oxide, zinc chloride, zinc sulfate, and zirconium oxide. Amongthese, zinc oxide is preferably used as an essential ingredient, and theformulation of zinc oxide contributes to a more definite expression ofthe effect of the present invention leading to improved thermal dryingcharacteristics and improved vibration damping properties. The level ofuse of zinc oxide is preferably 0.1 to 20 weight parts based on 100weight parts of the emulsion solids. Thus, the preferred amount of zincoxide in the emulsion composition for vibration damping materials basedon 100 weight parts of the total emulsion solids is 0.1 to 20 weightparts, more preferably 0.1 to 15 weight parts, and still more preferablyover 3 weight parts but not over 15 weight parts. It is also goodpractice to formulate zirconium oxide as an essential component of theformulation, for it contributes to a further improvement in thestability of the emulsion composition for vibration damping materials.The level of use of zirconium oxide based on 100 weight parts of thetotal emulsion solids is 0.1 to 20 weight parts. The more preferredlevel is 0.1 to 15 weight parts and the still more preferred level isover 1 weight part but not over 15 weight parts.

The crosslinking agent can be used in a powdery form or in the form ofan aqueous dispersion. Between these alternative forms, the use of anaqueous dispersion leads to better dispersiblity of the crosslinkingagent in a damper formulation comprising said emulsion composition forvibration damping materials as an essential ingredient as well asimproved long-term storage stability of the formulation. Therefore, itis preferably used as dispersed in water with the aid of an emulsifier.When the crosslinking agent is used in the form of such an emulsifiedaqueous dispersion, it is well dispersible in the emulsion so that theeffect attributable to the combination of the emulsion and thecrosslinking agent is sufficiently expressed. As a result, the stabilityand dispersibility of a damper formulation containing the emulsioncomposition for vibration damping materials of the present invention asan essential ingredient are enhanced so that not only thermal dryingcharacteristics but also vibration damping properties are improved.

In the second-mentioned emulsion composition for vibration dampingmaterials or emulsion composition for chipping-resistant materials (2),the monomer composition contains an unsaturated monomer having two ormore functional groups as an essential component. While the emulsioncomposition for vibration damping materials or emulsion composition forchipping-resistant materials containing such a monomer as an essentialcomponent is useful for both vibration-damping materials andchipping-resistant materials, it is particularly suited to the vibrationdamping materials.

The functional groups of said unsaturated monomer having two or morefunctional groups may be any groups that are capable of crosslinkingduring production of the emulsion by copolymerization. By virtue of suchfunctional groups, the emulsion composition for vibration dampingmaterials and the emulsion composition for chipping-resistant materialsare improved in film-forming properties and thermal dryingcharacteristics. In the present invention, because the monomercomposition mentioned above contains an unsaturated monomer having twoor more functional groups as an essential component, the effectattributable to this unsaturated monomer having functional groups isfully expressed. Moreover, the monomer composition may or may notadditionally contain an unsaturated monomer having only one functionalgroup.

The preferred functional group includes epoxy, oxazoline, carbodiimide,aziridinyl, isocyanato, methylol, vinyl ether, cyclocarbonate, andalkoxysilane groups. Only one or a plurality of species of thesefunctional groups may occur in each molecule of the unsaturated monomer.

The preferred species of said unsaturated monomer having two or morefunctional groups includes the following polyfunctional unsaturatedmonomers: divinylbenzene, ethylene glycol di(meth)acrylate,N-methoxymethyl(meth)acrylamide, N-methxoyethyl(meth)acrylamide,N-n-butoxymethyl(meth)acrylamide, N-i-butoxymethyl(meth)acrylamide,N-methylol(meth)acrylamide, diallyl phthalate, diallyl terephthalate,polyethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate,polypropylene glycol di(meth)acrylate, tetramethylene glycoldi(meth)acrylate, polytetramethylene glycol di(meth)acrylate,1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, andso on. Among these, unsaturated monomers having three or more functionalgroups are advantageous in that the effect of the present invention ismore fully expressed. As regards said unsaturated monomer having onlyone functional group, glycidyl group-containing unsaturated monomerssuch as glycidyl(meth)acrylate and acryloyl glycidyl ether arepreferred. These can be used each independently or in a combination oftwo or more species.

The emulsion according to the present invention is a water-based systemconsisting of water as a continuous phase, where a polymer formed froman unsaturated carboxylic acid monomer as an essential monomer and/or apolymer formed from an unsaturated monomer having two or more functionalgroups as an essential monomer is dispersed. Usually, a substrate iscoated with such a damper formulation comprising said emulsioncomposition for vibration damping materials as an essential ingredientto provide a vibration damping material or with a chipping-resistantformulation comprising said emulsion composition for chipping-resistantmaterials as an essential ingredient to provide a chipping-resistantmaterial. The vibration damping material and the chipping-resistantmaterial formed from an emulsion will hereinafter be referred tosometimes as a water-based vibration damping material and a water-basedchipping-resistant material, respectively.

The monomer composition which is to form the emulsion according to thepresent invention comprises an unsaturated carboxylic acid monomerand/or an unsaturated monomer having two or more functional groups as anessential component and may optionally contain other monomerscopolymerizable with said unsaturated carboxylic acid monomer andunsaturated monomer having two or more functional groups substantiallywithout restriction unless the expression of the effect of the presentinvention is thereby undermined. The preferred emulsion contains saidunsaturated carboxylic acid monomer and/or unsaturated monomer havingtwo or more functional groups and one or more other monomerscopolymerizable with the above essential monomers. It is also preferablethat, in the emulsion of the present invention, said monomers have been“copolymerized”.

The unsaturated carboxylic acid monomer referred to above is notparticularly restricted insofar as it is a compound having anunsaturated bond and a carboxyl group within the molecule. However, itis preferable to use an ethylenically unsaturated carboxylic acidmonomer. Thus, one of the preferred embodiments of the present inventionis an emulsion composition for vibration damping materials or anemulsion composition for chipping-resistant materials, which comprisesan emulsion prepared by polymerizing a monomer composition containing anethylenically unsaturated carboxylic acid monomer as an essentialcomponent.

In the present invention, it is also preferable that the monomercomposition contains an acrylic monomer as an essential component. Theacrylic monomer which can be used includes (meth)acrylic acid and(meth)acrylic acid derivatives such as (meth)acrylic acid esters.

The proportion of such acrylic monomer or monomers in the monomercomposition is preferably not less than 50 mass % of the total monomercomposition. From the standpoint of vibration damping properties andchipping-resistant properties, the conjugated diene monomer content ofsuch a monomer composition is preferably not more than 10 mass % of thetotal monomer composition, more preferably not more than 5 mass %. It ismost preferably that the monomer composition does not contain anyconjugated diene monomer.

In the present invention, said monomer composition is preferably acomposition in which said unsaturated monomer having two or morefunctional groups accounts for less than 10 mass %, preferably 0.1 to3.0 mass %, of the total monomer composition.

The above mass percentage figures are based on 100 mass % of the totalmonomer composition.

Furthermore, in the present invention, said monomer composition ispreferably composed of 0.1 to 20 mass % of an ethylenically unsaturatedcarboxylic acid monomer and 99.9 to 80 mass % of other copolymerizableethylenically unsaturated monomer. On account of the inclusion of anethylenically unsaturated carboxylic acid monomer, the dispersibility ofa filler, such as an inorganic powder, in the damper formulation orchipping-resistant formulation containing said emulsion composition forvibration damping materials or emulsion composition forchipping-resistant materials as an essential ingredient is improved toenhance vibration damping properties or chipping-resistant properties.Furthermore, by formulating said other copolymerizable ethylenicallyunsaturated monomer, it is made easier to adjust the Tg and otherphysical properties of the emulsion composition for vibration dampingmaterials or the emulsion composition for chipping-resistant materials.If the proportion of the ethylenically unsaturated carboxylic acidmonomer in said monomer composition is either less than 0.1 mass % orexceeds 20 mass %, no stable copolymerization of the emulsion may beachieved.

In the emulsion composition for vibration damping materials or theemulsion composition for chipping-resistant materials, the synergism ofeffects of the monomer units derived from such monomers insuressufficient expression of good thermal drying characteristics andvibration damping properties in the production of a water-basedvibration damping material or good thermal drying characteristics andchipping-resistant properties in the production of a water-basedchipping-resistant material.

The mass percentage figures mentioned above are based on 100 mass % ofthe total monomer composition.

As the ethylenically unsaturated carboxylic acid monomer referred toabove, it is preferable to use one or more members selected from thegroup consisting of unsaturated carboxylic acids and derivativesthereof, such as (meth)acrylic acid, crotonic acid, itaconic acid,fumaric acid, maleic acid, monomethyl fumarate, monoethyl fumarate,monomethyl maleate, monoethyl maleate and so on.

As said other copolymerizable ethylenically unsaturated monomer ormonomers, it is preferable to use one or more species of the functionalgroup-containing unsaturated monomers mentioned above; (meth)acrylicacid esters such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl(meth)acrylate, 2-ethylhexyl (meth)acrylate, cyclohexyl (meth)acrylate,etc.; and aromatic unsaturated monomers such as styrene.

When the number average molecular weight of said emulsion is small, themutual affinity of the filler, e.g. an inorganic powder, and theemulsion is enhanced to improve dispersibility in the damper formulationor chipping-resistant formulation containing the emulsion compositionfor vibration damping materials or the emulsion composition forchipping-resistant materials of the present invention which contains theemulsion as an essential ingredient.

The emulsion according to the present invention preferably has a glasstransition temperature (Tg) of −50° C. to 40° C. If it is below −50° C.or over 40° C., sufficient vibration damping or chipping-resistanteffects may not be expressed. The more preferred Tg range is −10 to 35°C. The Tg of an emulsion can be calculated from the Tg values ofhomopolymers of the respective monomers constituting the emulsion.

The emulsion according to the present invention preferably has a gelfraction of 0 to 45 mass % as determined in the solvent toluene. The gelfraction in the context of the present invention is an indexrepresenting the solubility of the film formed from the emulsion in thesolvent toluene, and the higher the gel fraction value is, the lower isthe solubility in the solvent toluene. The gel fraction reflects themolecular structure of a resin and if the gel fraction of the emulsionexceeds 45 mass %, vibration damping properties or chipping-resistantproperties may not be fully expressed when the emulsion is used in adamper formulation or a chipping-resistant formulation. Moreover, thetemperature dependency of vibration damping properties orchipping-resistant properties is increased so that, for example, a peakof damping effect or a peak of chipping-resistant effect will appear ina limited temperature region. In order to insure expression of goodvibration damping properties or chipping-resistant properties, the gelfraction of the emulsion is preferably controlled within the range of 5to 45 mass %, more preferably 0 to 30 mass %.

The gel fraction referred to above is preferably determined by a methodof quantitating toluene-insolubles, for example as described below.

<Method for Determination of the Gel Fraction (Toluene-Insolubles)>

The emulsion is cast into a 0.2 cm-deep frame on a sheet of releasingpaper to mold a 0.2 cm-thick film. This film was cut to 2 cm (L)×2 cm(W)×0.2 cm (T) to prepare a test film. This test film was immersed in100 ml of toluene and agitated for 6 hours using a magnetic stirrer atroom temperature. The mixture was then filtered through a 100-mesh metalsieve and the solid matter of the filtrate is quantitated to calculatethe gel fraction.

The emulsion mentioned above is preferably such that when it isformulated into a damper formulation as described above, the loss factor(loss tangent: tan δ) of the damper formulation will be not less than0.15. Thus, when the emulsion according to the present invention isformulated into a damper formulation described below, the loss factor(tan δ) of the film formed from the damper formulation is preferably notless than 0.15. The vibration damping properties, that is loss factor,of the film is correlated with the tan δ of the film used, and thehigher the tan δ value of the film is, the higher is the vibrationdamping properties of the film.

If said loss factor (tan δ) is less than 0.15, acceptable vibrationdamping properties may not be expressed in a water-based vibrationdamping material. The loss factor is more preferably not less than 0.16,still more preferably not less than 0.18.

<Composition of the Damper Formulation>

Emulsion 100 weight parts

Calcium carbonate: NN#200 (trademark, product of Nitto Powder IndustryCo.) 250 weight parts

Dispersant: Demol EP (trademark, product of Kao Corporation) 1 weightpart

Thickener: Acryset WR-600 (trademark, Nippon Shokubai Co.) 2 weightparts

Antifoaming agent: Nopco 8034L (trademark, product of Sun Nopco Co.) 0.3weight part

<Method for Determination of Loss Factor (tan δ)>

The above damper formulation was poured into a 3 mm-deep frame on acationically electrocoated steel panel (15 mm (W)×250 mm (L)×0.8 mm (T))and dried at 150° C. for 30 minutes to prepare a testpiece. Using OnoInstrument's loss factor determination system and a cantilever method,the loss factor of the testpiece in a 25° C. measuring environment wasdetermined.

The process for producing the above emulsion is described below.

The above emulsion is prepared by polymerizing a monomer compositioncomprising an unsaturated carboxylic acid monomer and/or an unsaturatedmonomer having two or more functional groups as an essential component.The emulsion polymerization method can be used advantageously forpolymerizing the monomer composition. The mode of emulsionpolymerization may comprise adding the monomer composition, apolymerization initiator and a surfactant to an aqueous mediumjudiciously and conducting the polymerization reaction. For molecularweight adjustment, a chain transfer agent may be employed.

The aqueous medium mentioned above is preferably water, a mixturesolvent composed of one or more water-miscible solvents, or a mixturesolvent consisting of such a solvent and a predominant proportion ofwater. Among these, water is preferred.

As the polymerization initiator mentioned above, the known water-solubleor oil-soluble initiator, such as ammonium persulfate, potassiumpersulfate, hydrogen peroxide, butyl hydroperoxide or the like, can beused with advantage. To accelerate the emulsion polymerization, a redoxinitiator system may be formed by adding sodium hydrogensulfite orL-ascorbic acid as a reducing agent. These may be used eachindependently or in a combination of two or more species.

The level of use of said polymerization initiator may be judiciouslyselected according to the kind of initiator but, based on 100 weightparts of the total monomer composition, is preferably 0.1 to 2 weightparts, more preferably 0.2 to 1 weight part.

The surfactant mentioned above may be any of anionic, nonionic, andnonionic-anionic emulsifiers. In terms of the stability of emulsionpolymerization, nonionic emulsifiers and nonionic-anionic emulsifiersare preferred among them, and more preferably a nonionic emulsifier anda nonionic-anionic emulsifier are used together. The anionic emulsifierincludes fatty acid soaps, rosin soaps, alkylsulfonic acid soaps,dialkylarylsulfonate, alkylsulfosuccinate, andpolyoxyethylene-alkylsulfate, among others. The nonionic emulsifierincludes polyoxyethylene alkyl ethers, polyoxyethylene alkylaryl ethers,polyoxyethylene sorbitan fatty acid esters, and oxyethylene-oxypropyleneblock copolymers, among others. These surfactants can be used eachindependently or in a combination of two or more species.

The level of use of such surfactant can be judiciously selectedaccording to the kind of surfactant, among other factors, but based on100 weight parts of the total monomer composition, is preferably 0.05 to5.0 weight parts, more preferably 0.1 to 3 weight parts.

The polymerization chain transfer agent includes alkylmercaptans, e.g.hexylmercaptan, octylmercaptan, n-dodecylmercaptan, t-dodecylmercaptan,n-hexadecylmercaptan, n-tetradecylmercaptan, etc.; halogenatedhydrocarbons, e.g. carbon tetrachloride, carbon tetrabromide, ethylenebromide, etc.; mercaptocarboxylic acid alkyl esters, e.g. 2-ethylhexylmercaptoacetate, 2-ethylhexyl mercaptopropionate, tridecylmercaptopropionate, etc.; mercaptocarboxylic acid alkoxyalkyl esters,e.g. methoxybutyl mercaptoacetate, methoxybutyl mercaptopropionate,etc.; carboxylic acid mercaptoalkyl esters, e.g. 2-mercaptoethyloctanoate etc.; α-methylstyrene dimer, terpinolene, α-terpinene,γ-terpinene, dipentene, anisole, and allyl alcohol, to mention somepreferred examples. These can be used each independently or in acombination of two or more species. Among these, it is preferable to usean alkylmercaptan such as hexylmercaptan, octylmercaptan,n-dodecylmercaptan, t-dodecylmercaptan, n-hexadecylmercaptan,n-tetradecylmercatan or the like. The level of use of the polymerizaitnchain transfer agent based-on 100 weight parts of the total monomercomposition is generally 0 to 1 weight part, preferably 0 to 0.5 weightpart.

The above emulsion polymerization may be carried out in the presence ofa chelating agent such as sodium ethylenediaminetetracetate, adispersant such as poly(sodium acrylate), and/or an inorganic salt. Asto the mode of addition of the monomers, polymerization initiator, etc.,any of en bloc addition, continuous addition, multistage addition, etc.may be employed. These modes of addition may be used in a suitablecombination.

Regarding the reaction conditions to be used for said emulsionpolymerization, the optimum conditions can be selected according to themonomer formulation, the kind of polymerization initiator, and otherfactors. The polymerization temperature is preferably 5 to 90° C., morepreferably 20 to 85° C. The preferred polymerization time is 3 to 8hours. The polymerization and dropwise additions are preferably carriedout under stirring.

In the above process, the emulsion prepared by emulsion polymerizationas above is preferably neutralized with a neutralizing agent, wherebythe emulsion is stabilized. The neutralizing agent which can be employedincludes tertiary amines, such as triethanolamine, dimethylethanolamine,diethylethanolamine, morpholine, etc.; aqueous ammonia; sodiumhydroxide; and so forth. These can be used each independently or in acombination of two or more species. Among these, volatile bases whichwill be evaporated off on heating in the thermal drying of the film arepreferred because these are conducive to an enhancement in the waterresistance of the film formed from a damper formulation orchipping-resistant formulation containing said emulsion as an essentialingredient. More preferably, it is advantageous to use an amine whoseboiling point at 80 to 360° C., for it contributes to improved thermaldrying characteristics and improved vibration damping properties orchipping-resistant properties. Thus, as the neutralizing agent, atertiary amine such as triethanolamine, dimethylethanolamine,diethylethanolamine, morpholine or the like is preferred. Morepreferably, an amine whose boiling point at 130 to 280° C. is employed.

The boiling point referred to above is the boiling point at atmosphericpressure.

The preferred level of addition of said neutralizing agent is 0.6 to 1.4equivalents relative to the acid value of the emulsion, namely to 1equivalent of the acid radical in the emulsion. The more preferred levelis 0.8 to 1.2 equivalents.

The emulsion composition for vibration damping materials or the emulsioncomposition for chipping-resistant materials as provided by the presentinvention can be formulated with various additives and a solvent toconstitute a damper formulation or a chipping-resistant formulation.Such a vibraiton damping formulation or a chipping-resistant formulationcontaining the above-described emulsion composition for vibrationdamping materials or emulsion composition for chipping-resistantmaterials of the present invention as an essential ingredient constituteanother preferred embodiment of the present invention, and each iscapable of expressing excellent thermal drying characteristics as wellas good vibration damping properties or chipping-resistant properties toform a water-based vibration damping material or a water-basedchipping-resistant material.

The formulating level of said emulsion composition for vibration dampingmaterials in the above damper formulation is preferably that solids ofthe emulsion composition for vibration damping materials, relative to100 mass % solids of the total damper formulation, is 30 to 60 mass %.The concentration of solids in the damper formulation as such ispreferably 10 to 40 mass % based on 100 mass % of the damperformulation.

As said additives, there can be mentioned the filler, colorant, aseptic,dispersant, thickener, thioxtropic agent, antifreezing agent, pH controlagent, antifoam, wetting agent, rust inhibitor, and adhesive mass, amongothers. These may be used each alone or in a combination of two or morespecies. Among these, the filler is preferably formulated.

The filler mentioned above includes inorganic fillers such as calciumcarbonate, kaolin, silica, talc, barium sulfate, alumina, iron oxide,titanium oxide, glass powder, etc.; flaky inorganic fillers such asglass flakes, mica, etc.; and filamentous inorganic fillers such asmetal oxide whiskers, glass fibers and so forth.

The formulating level of said filler is preferably 50 to 400 weightparts based on 100 weight parts of emulsion solids. The more preferredlevel is 100 to 350 weight parts on the same basis.

The solvent mentioned above is not particularly restricted provided thatthe operation and effect of the present invention can be insured, andone or more solvent species can be employed. The formulating level ofthe solvent may, for example, be so selected that the concentration ofsolids in the damper formulation will fall within the above-mentionedrange.

The equipment that can be used for the production of the above damperformulation includes the butterfly mixer, planetary mixer, spiral mixer,kneader, Dissolver and so on.

The above damper formulation, when it contains the second-mentionedemulsion composition for vibration damping materials (2), too,preferably contains a polyvalent metal oxide together with said emulsioncomposition for vibration damping materials. By formulating the metaloxide, the stability, dispersibility, and thermal drying characteristicsof the damper formulation and the vibration damping properties of thevibration damping material formed from the damper formulation can beimproved. The preferred species and form of the polyvalent metal oxideare the same as those mentioned hereinbefore.

In the present invention, by incorporating the polyvalent metal oxide inthe damper formulation, the thermal drying properties of the compoundconstituting the damper formulation can be improved and the vibrationdamping properties of the vibration damping material formed from such adamper formulation containing a polyvalent metal oxide as an essentialcomponent is improved. The polyvalent metal oxide thus contained in thedamper formulation constitutes one of the preferred embodiments of thepresent invention.

Regarding said polyvalent metal oxide, one or more species can beemployed and the preferred form is the same as described hereinbefore.The preferred ingredient to be formulated into the damper formulationalong with said polyvalent metal oxide, that is to say the otheringredient to constitute the damper formulation, is the emulsiondescribed above.

The formulating level of the emulsion composition for chipping-resistantmaterials in the chipping-resistant formulation which is to form saidchipping-resistant material is preferably 30 to 60 mass % in terms ofemulsion solids based on 100 mass % of the total solids of thechipping-resistant formulation. The concentration of solids in thechipping-resistant formulation is preferably 10 to 40 mass % based on100 mass % of the chipping-resistant formulation.

The additives may be the same as those mentioned hereinbefore and it ispreferable that a filler is formulated. The formulating level of thefiller in the chipping-resistant formulation is preferably 50 to 400weight parts, more preferably 100 to 350 weight parts, based on 100weight parts of the solids of the emulsion composition forchipping-resistant materials.

The above chipping-resistant formulation, too, preferably contains apolyvalent metal oxide along with said emulsion composition forchipping-resistant materials. By formulating a polyvalent metal oxide,the stability, dispersibility and thermal drying characteristics of thechipping-resistant formulation and the chipping-resistant properties ofthe chipping-resistant material formed from said chipping-resistantformulation can be improved. The polyvalent metal oxide includes thesame compounds as mentioned hereinbefore and, among them, zinc oxide andzirconium oxide are preferred. The form of said polyvalent metal oxidemay also be the same as that described above and in view of betterdispersibility of ingredients in the chipping-resistant formulation, themetal oxide is preferably used in the form of an aqueous dispersion oran emulsified dispersion. The more preferred is an emulsifieddispersion. The level of use of the polyvalent metal oxide is preferably0.05 to 5.0 weight parts based on 100 weight parts of the solids in theemulsion composition for chipping-resistant materials. The morepreferred level is 0.05 to 3.5 weight parts.

The solvent mentioned above is not particularly restricted insofar asthe operation and effect of the present invention are not compromised,and one or more solvent species can be employed. The formulating amountof the solvent can be selected so that the concentration of solids inthe chipping-resistant formulation will fall within the above-mentionedrange.

The method of producing said emulsion composition for vibration dampingmaterials or emulsion composition for chipping-resistant materials ofthe present invention, which is to be used for the production of adamper formulation containing the first-mentioned emulsion compositionfor vibration damping materials (1) as an essential ingredient, needonly be such that the resulting damper formulation will contain theessential ingredients of the emulsion composition for vibration dampingmaterials of the present invention, namely said emulsion andcrosslinking agent. The preferred specific technology includes (a) themethod which comprises preparing an emulsion composition for vibrationdamping materials in the form of a premix with a crosslinking agent andadmixing the premix with said various additives, solvent, etc. to give adamper formulation containing said emulsion composition for vibrationdamping materials as an essential ingredient and (b) the method inwhich, without premixing said emulsion with the crosslinking agent, theadditives, solvent and others are mixed with the essential ingredientsas necessary to produce a damper formulation containing said emulsioncomposition for vibration damping materials as an essential ingredients.In these methods, the order of additions is not particularly restricted.

The damper formulation or chipping-resistant formulation containing thesecond-mentioned emulsion composition for vibration damping materials oremulsion composition for chipping-resistant materials (2) as anessential ingredient can be produced by admixing said emulsioncomposition for vibration damping materials or emulsion composition forchipping-resistant materials with said additives, solvent and others.

The preferred equipment for use in the production of said damperformulation or chipping-resistant formulation includes the butterflymixer, planetary mixer, spiral mixer, kneader and Dissolver, amongothers.

The above damper formulation exhibits excellent thermal dryingcharacteristics and vibration damping properties and forms a water-basedvibration damping material. The above chipping-resistant formulationexhibits very satisfactory thermal drying characteristics andchipping-resistant properties and forms a water-based chipping-resistantmaterial. The vibration damping material formed from the damperformulation containing the emulsion composition for vibration dampingmaterials of the present invention as an essential ingredient and thechipping-resistant material formed from the chipping-resistantformulation containing the emulsion composition for chipping-resistantmaterials of the present invention as an essential ingredient constitutea further preferred embodiment of the present invention.

The above damper formulation or chipping-resistant formulation is coatedon a substrate and dried to give a film constituting said vibrationdamping material or chipping-resistant material. The substrate is notparticularly restricted. As regards the method of coating a substratewith said damper formulation or chipping-resistant formulation, thebrush, spatula, air spray gun, airless spray gun, mortar gun, texturegun, etc. can be used for coating.

The coating amount of the above damper formulation or chipping-resistantformulation may be selected according to the intended application andexpected performance, among other variables. In the case where thevibration damping material is to be formed by using the damperformulation as a coating, for instance, the dry thickness of the coatingis preferably 0.5 to 5.0 mm, more preferably 1.5 to 4.5 mm. In the casewhere the chipping-resistant material is to be formed by using thechipping-resistant formulation as a coating, for instance, the drythickness of the coating is preferably 0.5 to 5.0 mm, more preferably1.5 to 4.5 mm.

Regarding the conditions to be used in the case where said damperformulation or chipping-resistant formulation is coated on a substrateand dried to form a film, either drying by heating or drying atatmospheric temperature can be adopted. However, from efficiency pointsof view, drying by heating is preferred. This is especially true becausethe formulations according to the present invention have excellentthermal drying characteristics. The temperature of said drying byheating for the formation of a vibration damping material is preferably80 to 210° C., more preferably 110 to 160° C. For the formation of achipping-resistant material, too, the drying temperature is preferably80 to 210° C., more preferably 110 to 160° C.

Since the damper formulation containing the emulsion composition forvibration damping materials of the present invention as an essentialingredient exhibits excellent thermal drying characteristics andvibration damping properties, it can be used with great advantage insuch applications as automotive cabin floor base, rolling stock, ships,aircraft, electric machinery, buildings and construction machinery,among others. The chipping-resistant formulation containing the emulsioncomposition for chipping-resistant materials of the present invention asan essential ingredient exhibits excellent thermal dryingcharacteristics and chipping-resistant properties and, therefore, can beapplied with great advantage to automotive exteriors, automotive parts,household electrical appliances and machines, among others.

The emulsion composition for vibration damping materials and emulsioncomposition for chipping-resistant materials of the present invention,each constituted as above, can be used with great advantage asingredients in damper formulations and chipping-resistant formulations,respectively. Moreover, the damper formulation containing such emulsioncomposition for vibration damping materials as an essential ingredientexhibits excellent thermal drying characteristics and vibration dampingproperties and forms water-based vibration damping materials, thusfinding application in such fields of use as automotive cabin floorbase, rolling stock, ships, aircraft, electric machinery, buildings andconstruction machinery, among other uses. Further, thechipping-resistant formulation containing the emulsion composition forchipping-resistant materials of the present invention as an essentialingredient exhibit excellent thermal drying characteristics andchipping-resistant properties and forms water-based chipping-resistantmaterials so that these can be used with great advantage in a variety offields such as automotive exteriors, automotive parts, householdelectrical appliances, and machines, among others.

BEST MODE FOR CARRYING OUT THE INVENTION EXAMPLES

The following examples illustrate the present invention in furtherdetail without defining the scope of the invention. It should beunderstood that unless otherwise indicated, all “parts” are “weightparts” and “%” means “mass %”.

Example 1

A separable flask equipped with a stirrer, reflux condenser,thermometer, nitrogen gas inlet pipe and dropping funnel was chargedwith 171.7 parts of deionized water. Then, under stirring in a nitrogengas stream, the contents of the flask were heated to an internaltemperature of 70° C. On the other hand, the dropping funnel was chargedwith a monomer emulsion composed of 53.3 parts of methyl methacrylate,245.0 parts of styrene, 189.2 parts of 2-ethylhexyl acrylate, 5.0 partsof divinylbenzene, 7.5 parts of acrylic acid, 20.0 parts of 25% aqueoussolution of Nonipol 200 (trademark, a polyoxyethylene phenyl ether,product of Sanyo Chemical Industries Co.), 50.0 parts of 20% aqueoussolution of Hitenol N-08 (trademark, a polyoxyethylene alkyl ethersulfate ester salt; product of Dai-Ichi Kogyo Seiyaku Co.) and 106.5parts of deionized water. Then, with the separable flask being held atan internal temperature of 70° C., the above monomer emulsion was addeduniformly dropwise over 3 hours. At the same time, 65.8 parts of 3.9%aqueous solution of potassium persulfate and 60 parts of 2% aqueoussolution of sodium hydrogensulfite were added uniformly dropwise over 3hours. After completion of dropwise addition, the reaction mixture wasincubated for ripening at 76° C. for 3 hours. After cooling, 4.7 partsof 25% aqueous ammonia was added. The emulsion was cooled and taken outthrough a 100-mesh stainless steel filter screen, whereby an aqueousresin (copolymer emulsion) was obtained. The nonvolatile matter content,pH and viscosity of the aqueous resin thus obtained were 53.1%, pH 8.9and 190 mPa·s, respectively.

Example 2

A separable flask equipped with a stirrer, reflux condenser,thermometer, nitrogen gas inlet pipe and dropping funnel was chargedwith 171.7 parts of deionized water. Then, under stirring in a nitrogengas stream, the contents of the flask were heated to an internaltemperature of 70° C. On the other hand, the dropping funnel was chargedwith a monomer emulsion composed of 53.3 parts of methyl methacrylate,240.0 parts of styrene, 189.2 parts of 2-ethylhexyl acrylate, 5.0 partsof trimethylolpropane trimethacrylate, 7.5 parts of acrylic acid, 20.0parts of 25% aqueous solution of Nonipol 200 (trademark, apolyoxyethylene phenyl ether, product of Sanyo Chemical Industries Co.),50.0 parts of 20% aqueous solution of Hitenol N-08 (trademark, apolyoxyethylene alkyl ether sulfate ester salt; product of Dai-IchiKogyo Seiyaku Co.) and 106.5 parts of deionized water. Then, with theseparable flask being held at an internal temperature of 70° C., theabove monomer emulsion was added uniformly dropwise over 3 hours. At thesame time, 65.8 parts of 3.9% aqueous solution of potassium persulfateand 60 parts of 2% aqueous solution of sodium hydrogensulfite were addeduniformly dropwise over 3 hours. After completion of dropwise addition,the reaction mixture was incubated for ripening at 76° C. for 3 hours.After cooling, 4.7 parts of 25% aqueous ammonia was added. The emulsionwas cooled and taken out through a 100-mesh stainless steel filterscreen, whereby an aqueous resin (copolymer emulsion) was obtained. Thenonvolatile matter content, pH and viscosity of the aqueous resin thusobtained were 53.1%, pH 8.8 and 200 mPa·s, respectively.

Example 3

A separable flask equipped with a stirrer, reflux condenser,thermometer, nitrogen gas inlet pipe and dropping funnel was chargedwith 171.7 parts of deionized water. Then, under stirring in a nitrogengas stream, the contents of the flask were heated to an internaltemperature of 70° C. On the other hand, the dropping funnel was chargedwith a monomer emulsion composed of 53.3 parts of methyl methacrylate,240.0 parts of styrene, 189.2 parts of 2-ethylhexyl acrylate, 5.0 partsof trimethylolpropane trimethacrylate, 7.5 parts of acrylic acid, 20.0parts of 25% aqueous solution of Nonipol 200 (trademark, apolyoxyethylene phenyl ether, product of Sanyo Chemical Industries Co.),50.0 parts of 20% aqueous solution of Hitenol N-08 (trademark, apolyoxyethylene alkyl ether sulfate ester salt; product of Dai-IchiKogyo Seiyaku Co.) and 106.5 parts of deionized water. Then, with theseparable flask being held at an internal temperature of 70° C., theabove monomer emulsion was added uniformly dropwise over 3 hours. At thesame time, 65.8 parts of 3.9% aqueous solution of potassium persulfateand 60 parts of 2% aqueous solution of sodium hydrogensulfite were addeduniformly dropwise over 3 hours. After completion of dropwise addition,the reaction mixture was incubated for ripening at 76° C. for 3 hours.After cooling, 4.7 parts of 25% aqueous ammonia was added. Thereafter,7.3 parts of Bacote 20T2 (trademark, a zirconia dispersion containing20% ZrO₂, product of Nippon Shokubai Co.) was added, followed bystirring for 30 minutes. The emulsion was cooled and taken out through a100-mesh stainless steel filter screen, whereby an aqueous resin(copolymer emulsion) was obtained. The nonvolatile matter content, pHand viscosity of the aqueous resin thus obtained were 52.9%, pH 8.6 and110 mPa·s, respectively.

Example 4

A separable flask equipped with a stirrer, reflux condenser,thermometer, nitrogen gas inlet pipe and dropping funnel was chargedwith 171.7 parts of deionized water. Then, under stirring in a nitrogengas stream, the contents of the flask were heated to an internaltemperature of 70° C. On the other hand, the dropping funnel was chargedwith a monomer emulsion composed of 53.3 parts of methyl methacrylate,240.0 parts of styrene, 189.2 parts of 2-ethylhexyl acrylate, 5.0 partsof trimethylolpropane trimethacrylate, 7.5 parts of acrylic acid, 20.0parts of 25% aqueous solution of Nonipol 200 (trademark, apolyoxyethylene phenyl ether, product of Sanyo Chemical Industries Co.),50.0 parts of 20% aqueous solution of Hitenol N-08 (trademark, apolyoxyethylene alkyl ether sulfate ester salt; product of Dai-IchiKogyo Seiyaku Co.) and 106.5 parts of deionized water. Then, with theseparable flask being held at an internal temperature of 70° C., theabove monomer emulsion was added uniformly dropwise over 3 hours. At thesame time, 65.8 parts of 3.9% aqueous solution of potassium persulfateand 60 parts of 2% aqueous solution of sodium hydrogensulfite were addeduniformly dropwise over 3 hours. After completion of dropwise addition,the reaction mixture was incubated for ripening at 76° C. for 3 hours.After cooling, 4.7 parts of 25% aqueous ammonia was added. Thereafter,3.7 parts of Bacote 20T2 (trademark, a zirconia dispersion containing20% ZrO₂, product of Nippon Shokubai Co.) was added, followed bystirring for 30 minutes. The emulsion was cooled and taken out through a100-mesh stainless steel filter screen, whereby an aqueous resin(copolymer emulsion) was obtained. The nonvolatile matter content, pHand viscosity of the aqueous resin thus obtained were 52.9%, pH 8.9 and120 mPa·s, respectively.

Example 5

A separable flask equipped with a stirrer, reflux condenser,thermometer, nitrogen gas inlet pipe and dropping funnel was chargedwith 171.7 parts of deionized water. Then, under stirring in a nitrogengas stream, the contents of the flask were heated to an internaltemperature of 70° C. On the other hand, the dropping funnel was chargedwith a monomer emulsion composed of 53.3 parts of methyl methacrylate,240.0 parts of styrene, 189.2 parts of 2-ethylhexyl acrylate, 5.0 partsof trimethylolpropane trimethacrylate, 7.5 parts of acrylic acid, 20.0parts of 25% aqueous solution of Nonipol 200 (trademark, apolyoxyethylene phenyl ether, product of Sanyo Chemical Industries Co.),50.0 parts of 20% aqueous solution of Hitenol N-08 (trademark, apolyoxyethylene alkyl ether sulfate ester salt; product of Dai-IchiKogyo Seiyaku Co.) and 106.5 parts of deionized water. Then, with theseparable flask being held at an internal temperature of 70° C., theabove monomer emulsion was added uniformly dropwise over 3 hours. At thesame time, 65.8 parts of 3.9% aqueous solution of potassium persulfateand 60 parts of 2% aqueous solution of sodium hydrogensulfite were addeduniformly dropwise over 3 hours. After completion of dropwise addition,the reaction mixture was incubated for ripening at 76° C. for 3 hours.After cooling, 4.7 parts of 25% aqueous ammonia was added. Thereafter,2.4 parts of Bacote 20T2 (trademark, a zirconia dispersion containing20% ZrO₂, product of Nippon Shokubai Co.) was added, followed bystirring for 30 minutes. The emulsion was cooled and taken out through a100-mesh stainless steel filter screen, whereby an aqueous resin(copolymer emulsion) was obtained. The nonvolatile matter content, pHand viscosity of the aqueous resin thus obtained were 52.7%, pH 8.5 and100 mPa·s, respectively.

Example 6

A separable flask equipped with a stirrer, reflux condenser,thermometer, nitrogen gas inlet pipe and dropping funnel was chargedwith 171.7 parts of deionized water. Then, under stirring in a nitrogengas stream, the contents of the flask were heated to an internaltemperature of 70° C. On the other hand, the dropping funnel was chargedwith a monomer emulsion composed of 53.3 parts of methyl methacrylate,242.5 parts of styrene, 189.2 parts of 2-ethylhexyl acrylate, 2.5 partsof trimethylolpropane trimethacrylate, 7.5 parts of acrylic acid, 20.0parts of 25% aqueous solution of Nonipol 200 (trademark, apolyoxyethylene phenyl ether, product of Sanyo Chemical Industries Co.),50.0 parts of 20% aqueous solution of Hitenol N-08 (trademark, apolyoxyethylene alkyl ether sulfate ester salt; product of Dai-IchiKogyo Seiyaku Co.) and 106.5 parts of deionized water. Then, with theseparable flask being held at an internal temperature of 70° C., theabove monomer emulsion was added uniformly dropwise over 3 hours. At thesame time, 65.8 parts of 3.9% aqueous solution of potassium persulfateand 60 parts of 2% aqueous solution of sodium hydrogensulfite were addeduniformly dropwise over 3 hours. After completion of dropwise addition,the reaction mixture was incubated for ripening at 76° C. for 3 hours.After cooling, 4.7 parts of 25% aqueous ammonia was added. Thereafter,7.3 parts of Bacote 20T2 (trademark, a zirconia dispersion containing20% ZrO₂, product of Nippon Shokubai Co.) was added, followed bystirring for 30 minutes. The emulsion was cooled and taken out through a100-mesh stainless steel filter screen, whereby an aqueous resin(copolymer emulsion) was obtained. The nonvolatile matter content, pHand viscosity of the aqueous resin thus obtained were 53.1%, pH 8.8 and190 mPa·s, respectively.

Example 7

A separable flask equipped with a stirrer, reflux condenser,thermometer, nitrogen gas inlet pipe and dropping funnel was chargedwith 171.7 parts of deionized water. Then, under stirring in a nitrogengas stream, the contents of the flask were heated to an internaltemperature of 70° C. On the other hand, the dropping funnel was chargedwith a monomer emulsion composed of 53.3 parts of methyl methacrylate,242.5 parts of styrene, 189.2 parts of 2-ethylhexyl acrylate, 2.5 partsof trimethylolpropane trimethacrylate, 7.5 parts of acrylic acid, 20.0parts of 25% aqueous solution of Nonipol 200 (trademark, apolyoxyethylene phenyl ether, product of Sanyo Chemical Industries Co.),50.0 parts of 20% aqueous solution of Hitenol N-08 (trademark, apolyoxyethylene alkyl ether sulfate ester salt; product of Dai-IchiKogyo Seiyaku Co.) and 106.5 parts of deionized water. Then, with theseparable flask being held at an internal temperature of 70° C., theabove monomer emulsion was added uniformly dropwise over 3 hours. At thesame time, 65.8 parts of 3.9% aqueous solution of potassium persulfateand 60 parts of 2% aqueous solution of sodium hydrogensulfite were addeduniformly dropwise over 3 hours. After completion of dropwise addition,the reaction mixture was incubated for ripening at 76° C. for 3 hoursand cooled. Then, a mixture of 4.8 parts of deionized water and 9.3parts of dimethylethanolamine was added. Thereafter, 7.3 parts of Bacote20T2 (trademark, a zirconia dispersion containing 20% ZrO₂, product ofNippon Shokubai Co.) was added, followed by stirring for 30 minutes. Theemulsion was cooled and taken out through a 100-mesh stainless steelfilter screen, whereby an aqueous resin (copolymer emulsion) wasobtained. The nonvolatile matter content, pH and viscosity of theaqueous resin thus obtained were 52.5%, pH 8.7 and 210 mPa·s,respectively.

Example 8

A separable flask equipped with a stirrer, reflux condenser,thermometer, nitrogen gas inlet pipe and dropping funnel was chargedwith 171.7 parts of deionized water. Then, under stirring in a nitrogengas stream, the contents of the flask were heated to an internaltemperature of 70° C. On the other hand, the dropping funnel was chargedwith a monomer emulsion composed of 53.3 parts of methyl methacrylate,242.5 parts of styrene, 189.2 parts of 2-ethylhexyl acrylate, 2.5 partsof trimethylolpropane trimethacrylate, 7.5 parts of acrylic acid, 20.0parts of 25% aqueous solution of Nonipol 200 (trademark, apolyoxyethylene phenyl ether, product of Sanyo Chemical Industries Co.),50.0 parts of 20% aqueous solution of Hitenol N-08 (trademark, apolyoxyethylene alkyl ether sulfate ester salt; product of Dai-IchiKogyo Seiyaku Co.) and 106.5 parts of deionized water. Then, with theseparable flask being held at an internal temperature of 70° C., theabove monomer emulsion was added uniformly dropwise over 3 hours. At thesame time, 65.8 parts of 3.9% aqueous solution of potassium persulfateand 60 parts of 2% aqueous solution of sodium hydrogensulfite were addeduniformly dropwise over 3 hours. After completion of dropwise addition,the reaction mixture was incubated for ripening at 76° C. for 3 hoursand cooled. Then, a mixture of 3.1 parts of deionized water and 11.0parts of diethanolamine was added. Thereafter, 7.3 parts of Bacote 20T2(trademark, a zirconia dispersion containing 20% ZrO₂, product of NipponShokubai Co.) was added, followed by stirring for 30 minutes. Theemulsion was cooled and taken out through a 100-mesh stainless steelfilter screen, whereby an aqueous resin (copolymer emulsion) wasobtained. The nonvolatile matter content, pH and viscosity of theaqueous resin thus obtained were 52.5%, pH 8.5 and 230 mPa·s,respectively.

Example 9

A separable flask equipped with a stirrer, reflux condenser,thermometer, nitrogen gas inlet pipe and dropping funnel was chargedwith 171.7 parts of deionized water. Then, under stirring in a nitrogengas stream, the contents of the flask were heated to an internaltemperature of 70° C. On the other hand, the dropping funnel was chargedwith a monomer emulsion composed of 53.3 parts of methyl methacrylate,242.5 parts of styrene, 189.2 parts of 2-ethylhexyl acrylate, 2.5 partsof trimethylolpropane trimethacrylate, 7.5 parts of acrylic acid, 20.0parts of 25% aqueous solution of Nonipol 200 (trademark, apolyoxyethylene phenyl ether, product of Sanyo Chemical Industries Co.),50.0 parts of 20% aqueous solution of Hitenol N-08 (trademark, apolyoxyethylene alkyl ether sulfate ester salt; product of Dai-IchiKogyo Seiyaku Co.) and 106.5 parts of deionized water. Then, with theseparable flask being held at an internal temperature of 70° C., theabove monomer emulsion was added uniformly dropwise over 3 hours. At thesame time, 65.8 parts of 3.9% aqueous solution of potassium persulfateand 60 parts of 2% aqueous solution of sodium hydrogensulfite were addeduniformly dropwise over 3 hours. After completion of dropwise addition,the reaction mixture was incubated for ripening at 76° C. for 3 hoursand cooled. Then, a mixture of 4.8 parts of deionized water and 9.3parts of dimethylethanolamine was added. Thereafter, 5.0 parts of WS-600(trademark, oxazoline group-containing aqueous solution, product ofNippon Shokubai Co.) was added and the mixture was stirred for 30minutes. The emulsion was cooled and taken out through a 100-meshstainless steel filter screen, whereby an aqueous resin (copolymeremulsion) was obtained. The nonvolatile matter content, pH and viscosityof the aqueous resin thus obtained were 52.6%, pH 9.0 and 135 mPa·s,respectively.

Example 10

A separable flask equipped with a stirrer, reflux condenser,thermometer, nitrogen gas inlet pipe and dropping funnel was chargedwith 171.7 parts of deionized water. Then, under stirring in a nitrogengas stream, the contents of the flask were heated to an internaltemperature of 70° C. On the other hand, the dropping funnel was chargedwith a monomer emulsion composed of 53.3 parts of methyl methacrylate,242.5 parts of styrene, 189.2 parts of 2-ethylhexyl acrylate, 2.5 partsof trimethylolpropane trimethacrylate, 7.5 parts of acrylic acid, 20.0parts of 25% aqueous solution of Nonipol 200 (trademark, apolyoxyethylene phenyl ether, product of Sanyo Chemical Industries Co.),50.0 parts of 20% aqueous solution of Hitenol N-08 (trademark, apolyoxyethylene alkyl ether sulfate ester salt; product of Dai-IchiKogyo Seiyaku Co.) and 106.5 parts of deionized water. Then, with theseparable flask being held at an internal temperature of 70° C., theabove monomer emulsion was added uniformly dropwise over 3 hours. At thesame time, 65.8 parts of 3.9% aqueous solution of potassium persulfateand 60 parts of 2% aqueous solution of sodium hydrogensulfite were addeduniformly dropwise over 3 hours. After completion of dropwise addition,the reaction mixture was incubated for ripening at 76° C. for 3 hoursand cooled. Then, a mixture of 4.8 parts of deionized water and 9.3parts of dimethylethanolamine was added. Thereafter, 7.3 parts of K-2030(trademark, oxazoline group-containing emulsion, product of NipponShokubai Co.) was added and the mixture was stirred for 30 minutes. Theemulsion was cooled and taken out through a 100-mesh stainless steelfilter screen, whereby an aqueous resin (copolymer emulsion) wasobtained. The nonvolatile matter content, pH and viscosity of theaqueous resin thus obtained were 52.4%, pH 8.4 and 175 mPa·s,respectively.

Example 11

A separable flask equipped with a stirrer, reflux condenser,thermometer, nitrogen gas inlet pipe and dropping funnel was chargedwith 171.7 parts of deionized water. Then, under stirring in a nitrogengas stream, the contents of the flask were heated to an internaltemperature of 70° C. On the other hand, the dropping funnel was chargedwith a monomer emulsion composed of 53.3 parts of methyl methacrylate,242.5 parts of styrene, 189.2 parts of 2-ethylhexyl acrylate, 2.5 partsof glycidyl methacrylate, 7.5 parts of acrylic acid, 20.0 parts of 25%aqueous solution of Nonipol 200 (trademark, a polyoxyethylene phenylether, product of Sanyo Chemical Industries Co.), 50.0 parts of 20%aqueous solution of Hitenol N-08 (trademark, a polyoxyethylene alkylether sulfate ester salt; product of Dai-Ichi Kogyo Seiyaku Co.) and106.5 parts of deionized water. Then, with the separable flask beingheld at an internal temperature of 70° C., the above monomer emulsionwas added uniformly dropwise over 3 hours. At the same time, 65.8 partsof 3.9% aqueous solution of potassium persulfate and 60 parts of 2%aqueous solution of sodium hydrogensulfite were added uniformly dropwiseover 3 hours. After completion of dropwise addition, the reactionmixture was incubated for ripening at 76° C. for 3 hours and cooled.Then, a mixture of 4.8 parts of deionized water and 9.3 parts ofdimethylethanolamine was added. Thereafter, 7.3 parts of Bacote 20T2(trademark, a zirconia dispersion containing 20% ZrO₂, product of NipponShokubai Co.) was added, followed by stirring for 30 minutes. Theemulsion was cooled and taken out through a 100-mesh stainless steelfilter screen, whereby an aqueous resin (copolymer emulsion) wasobtained. The nonvolatile matter content, pH and viscosity of theaqueous resin thus obtained were 52.9%, pH 8.6 and 155 mPa·s,respectively.

Example 12

A separable flask equipped with a stirrer, reflux condenser,thermometer, nitrogen gas inlet pipe and dropping funnel was chargedwith 171.7 parts of deionized water. Then, under stirring in a nitrogengas stream, the contents of the flask were heated to an internaltemperature of 70° C. On the other hand, the dropping funnel was chargedwith a monomer emulsion composed of 53.3 parts of methyl methacrylate,242.5 parts of styrene, 189.2 parts of 2-ethylhexyl acrylate, 2.5 partsof trimethylolpropane trimethacrylate, 7.5 parts of acrylic acid, 1.0part of t-dodecylmercaptan, 20.0 parts of 25% aqueous solution ofNonipol 200 (trademark, a polyoxyethylene phenyl ether, product of SanyoChemical Industries Co.), 50.0 parts of 20% aqueous solution of HitenolN-08 (trademark, a polyoxyethylene alkyl ether sulfate ester salt;product of Dai-Ichi Kogyo Seiyaku Co.) and 106.5 parts of deionizedwater. Then, with the separable flask being held at an internaltemperature of 70° C., the above monomer emulsion was added uniformlydropwise over 3 hours. At the same time, 65.8 parts of 3.9% aqueoussolution of potassium persulfate and 60 parts of 2% aqueous solution ofsodium hydrogensulfite were added uniformly dropwise over 3 hours. Aftercompletion of dropwise addition, the reaction mixture was incubated forripening at 76° C. for 3 hours and cooled. Then, a mixture of 4.8 partsof deionized water and 9.3 parts of dimethylethanolamine was added.Thereafter, 7.3 parts of Bacote 20T2 (trademark, a zirconia dispersioncontaining 20% ZrO₂, product of Nippon Shokubai Co.) was added, followedby stirring for 30 minutes. The emulsion was cooled and taken outthrough a 100-mesh stainless steel filter screen, whereby an aqueousresin (copolymer emulsion) was obtained. The nonvolatile matter content,pH and viscosity of the aqueous resin thus obtained were 52.9%, pH 9.0and 200 mPa·s, respectively.

Example 13

A separable flask equipped with a stirrer, reflux condenser,thermometer, nitrogen gas inlet pipe and dropping funnel was chargedwith 171.7 parts of deionized water. Then, under stirring in a nitrogengas stream, the contents of the flask were heated to an internaltemperature of 70° C. On the other hand, the dropping funnel was chargedwith a monomer emulsion composed of 53.3 parts of methyl methacrylate,242.5 parts of styrene, 189.2 parts of 2-ethylhexyl acrylate, 2.5 partsof trimethylolpropane trimethacrylate, 7.5 parts of acrylic acid, 1.0part of t-dodecylmercaptan, 20.0 parts of 25% aqueous solution ofNonipol 200 (trademark, a polyoxyethylene phenyl ether, product of SanyoChemical Industries Co.), 50.0 parts of 20% aqueous solution of HitenolN-08 (trademark, a polyoxyethylene alkyl ether sulfate ester salt;product of Dai-Ichi Kogyo Seiyaku Co.) and 106.5 parts of deionizedwater. Then, with the separable flask being held at an internaltemperature of 70° C., the above monomer emulsion was added uniformlydropwise over 3 hours. At the same time, 65.8 parts of 3.9% aqueoussolution of potassium persulfate and 60 parts of 2% aqueous solution ofsodium hydrogensulfite were added uniformly dropwise over 3 hours. Aftercompletion of dropwise addition, the reaction mixture was incubated forripening at 76° C. for 3 hours and cooled. Then, a mixture of 4.8 partsof deionized water and 9.3 parts of dimethylethanolamine was added.Thereafter, 3.7 parts of Bacote 20T2 (trademark, a zirconia dispersioncontaining 20% ZrO₂, product of Nippon Shokubai Co.) was added and themixture was stirred for 30 minutes. The emulsion was cooled and takenout through a 100-mesh stainless steel filter screen, whereby an aqueousresin (copolymer emulsion) was obtained. The nonvolatile matter content,pH and viscosity of the aqueous resin thus obtained were 52.8%, pH 9.0and 180 mPa·s, respectively.

Example 14

A separable flask equipped with a stirrer, reflux condenser,thermometer, nitrogen gas inlet pipe and dropping funnel was chargedwith 171.7 parts of deionized water. Then, under stirring in a nitrogengas stream, the contents of the flask were heated to an internaltemperature of 70° C. On the other hand, the dropping funnel was chargedwith a monomer emulsion composed of 295.8 parts of styrene, 189.2 partsof 2-ethylhexyl acrylate, 2.5 parts of trimethylolpropanetrimethacrylate, 5.0 parts of acrylic acid, 1.0 part oft-dodecylmercaptan, 20.0 parts of 25% aqueous solution of Nonipol 200(trademark, a polyoxyethylene phenyl ether, product of Sanyo ChemicalIndustries Co.), 50.0 parts of 20% aqueous solution of Hitenol N-08(trademark, a polyoxyethylene alkyl ether sulfate ester salt; product ofDai-Ichi Kogyo Seiyaku Co.) and 106.5 parts of deionized water. Then,with the separable flask being held at an internal temperature of 70°C., the above monomer emulsion was added uniformly dropwise over 3hours. At the same time, 65.8 parts of 3.9% aqueous solution ofpotassium persulfate and 60 parts of 2% aqueous solution of sodiumhydrogensulfite were added uniformly dropwise over 3 hours. Aftercompletion of dropwise addition, the reaction mixture was incubated forripening at 76° C. for 3 hours and cooled. Then, a mixture of 4.8 partsof deionized water and 9.3 parts of dimethylethanolamine was added.Thereafter, 7.3 parts of Bacote 20T2 (trademark, a zirconia dispersioncontaining 20% ZrO₂, product of Nippon Shokubai Co.) was added and themixture was stirred for 30 minutes. The emulsion was cooled and takenout through a 100-mesh stainless steel filter screen, whereby an aqueousresin (copolymer emulsion) was obtained. The nonvolatile matter content,pH and viscosity of the aqueous resin thus obtained were 52.9%, pH 9.0and 200 mPa·s, respectively.

Comparative Example 1

A separable flask equipped with a stirrer, reflux condenser,thermometer, nitrogen gas inlet pipe and dropping funnel was chargedwith 171.7 parts of deionized water. Then, under stirring in a nitrogengas stream, the contents of the flask were heated to an internaltemperature of 70° C. On the other hand, the dropping funnel was chargedwith a monomer emulsion composed of 53.3 parts of methyl methacrylate,245.0 parts of styrene, 189.2 parts of 2-ethylhexyl acrylate, 5.0 partsof glycidyl methacrylate, 7.5 parts of acrylic acid, 20.0 parts of 25%aqueous solution of Nonipol 200 (trademark, a polyoxyethylene phenylether, product of Sanyo Chemical Industries Co.), 50.0 parts of 20%aqueous solution of Hitenol N-08 (trademark, a polyoxyethylene alkylether sulfate ester salt; product of Dai-Ichi Kogyo Seiyaku Co.) and106.5 parts of deionized water. Then, with the separable flask beingheld at an internal temperature of 70° C., the above monomer emulsionwas added uniformly dropwise over 3 hours. At the same time, 65.8 partsof 3.9% aqueous solution of potassium persulfate and 60 parts of 2%aqueous solution of sodium hydrogensulfite were added uniformly dropwiseover 3 hours. After completion of dropwise addition, the reactionmixture was incubated for ripening at 76° C. for 3 hours. After cooling,4.7 parts of 25% aqueous ammonia was added. The emulsion was cooled andtaken out through a 100-mesh stainless steel filter screen, whereby anaqueous resin (copolymer emulsion) was obtained. The nonvolatile mattercontent, pH and viscosity of the aqueous resin thus obtained were 53.0%,pH 8.6 and 150 mPa·s, respectively.

Comparative Example 2

A separable flask equipped with a stirrer, reflux condenser,thermometer, nitrogen gas inlet pipe and dropping funnel was chargedwith 171.7 parts of deionized water. Then, under stirring in a nitrogengas stream, the contents of the flask were heated to an internaltemperature of 70° C. On the other hand, the dropping funnel was chargedwith a monomer emulsion composed of 53.3 parts of methyl methacrylate,240.0 parts of styrene, 189.2 parts of 2-ethylhexyl acrylate, 10.0 partsof glycidyl methacrylate, 7.5 parts of acrylic acid, 20.0 parts of 25%aqueous solution of Nonipol 200 (trademark, a polyoxyethylene phenylether, product of Sanyo Chemical Industries Co.), 50.0 parts of 20%aqueous solution of Hitenol N-08 (trademark, a polyoxyethylene alkylether sulfate ester salt; product of Dai-Ichi Kogyo Seiyaku Co.) and106.5 parts of deionized water. Then, with the separable flask beingheld at an internal temperature of 70° C., the above monomer emulsionwas added uniformly dropwise over 3 hours. At the same time, 65.8 partsof 3.9% aqueous solution of potassium persulfate and 60 parts of 2%aqueous solution of sodium hydrogensulfite were added uniformly dropwiseover 3 hours. After completion of dropwise addition, the reactionmixture was incubated for ripening at 76° C. for 3 hours. After cooling,4.7 parts of 25% aqueous ammonia was added. The emulsion was cooled andtaken out through a 100-mesh stainless steel filter screen, whereby anaqueous resin (copolymer emulsion) was obtained. The nonvolatile mattercontent, pH and viscosity of the aqueous resin thus obtained were 53.1%,pH 8.8 and 130 mpa·s, respectively.

The emulsions obtained in Examples 1 to 14 and Comparative Examples 1and 2 were respectively subjected to the following evaluation tests. Theresults are shown in Table 1.

(Methods for Evaluation)

The copolymer emulsions obtained in Examples 1 to 14 and ComparativeExamples 1 and 2 were respectively formulated as shown hereunder toprepare damper formulations. These damper formulations were found tohave the properties indicated below.

Acrylic copolymer emulsion 148 parts

Calcium carbonate: NN#200 (trademark, product of Nitto Powder IndustryCo.) 240 parts

Additive: propylene glycol 19 parts

Dispersant: Demol EP (trademark, product of Kao Corporation) 4.3 parts

Thickener: Acryset WR-600 (trademark, product of Nippon Shokubai Co.) 7parts

Antifoaming agent: Nopco 8034L (trademark, product of Sun Nopco Co.) 0.3part

(1) Thermal Drying Test

Steel panels (trademark;SPCC-SD, 75 mm wide×150 mm long×0.8 mm thick,product of Nippon Test Panel Co.) were coated with the above-prepareddamper formulations in coating thicknesses of 1.5 mm, 3.0 mm and 4.5 mm,respectively. Then, using a hot-air dryer, the coatings were dried at150° C. for 30 minutes and the resulting dry films were evaluated forblistering (swelling) and cracking according to the following criteria.

Evaluation Criteria (Visual Evaluation)

-   ◯: Neither blistering nor cracking-   Δ: Few blisters and cracks-   X: Many blisters and cracks    (2) Loss Factor (tan δ)

Steel panels (trademark;SPCC-SD, 15 mm wide×250 mm long×0.8 mm thick,product of Nippon Test Panel Co.) were coated with the above-prepareddamper formulations. Then, using a hot-air dryer, the coatings weredried at 150° C. for 30 minutes. The coating amount was adjusted so thatthe thicknesses (dry thickness) of the damper formulation would be 1.5mm, 3.0 mm or 4.5 mm. The vibration damping properties was evaluated bymeasuring tan δ by the cantilever method in a measuring environment of25° C. using Ono Instrument's loss factor determination system. Thus,the larger the loss factor value is, the more satisfactory is thevibration damping properties.

TABLE 1 Examples Co. Examples 1 2 3 4 5 6 7 8 9 10 11 12 13 14 1 2Thermal 1.5 mm ◯ ◯ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ◯ ◯ drying 3.0 mm ◯ ◯ ⊚ ⊚ ◯ ◯⊚ ⊚ ◯ ◯ ◯ ⊚ ⊚ ⊚ X X character- 4.5 mm ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ ⊚ X Xistics Loss 1.5 mm 0.1 0.11 0.16 0.12 0.1 0.16 0.18 0.19 0.14 0.13 0.140.2 0.19 0.2 0.06 0.08 factor 3.0 mm 0.24 0.25 0.32 0.31 0.26 0.27 0.320.33 0.23 0.26 0.3 0.33 0.32 0.35 Not Not (tan δ) measurable measurableowing to owing to blistering cracking 4.5 mm 0.35 0.36 0.43 0.42 0.370.38 0.46 0.48 0.29 0.3 0.4 0.47 0.47 0.49 Not Not measurable measurableowing to owing to blistering blistering

1. An emulsion composition for vibration damping materials whichcomprises (i) an emulsion obtained by polymerizing a monomer compositioncontaining an unsaturated carboxylic acid monomer as an essentialcomponent and (ii) a crosslinking agent, wherein said monomercomposition contains 0.1 to 20 mass % of an ethylenically unsaturatedcarboxylic acid monomer and 99.9 to 80 mass % of other copolymerizableethylenically unsaturated monomer, said crosslinking agent is at leastone oxazoline compound, and is used in the form of an aqueous dispersionwith the aid of an emulsifier, wherein the emulsion has a glasstransition temperature of −50 to 40° C., and loss factor (loss tangent:tan δ) of a damper formulation formulated by the emulsion compositionfor vibration damping materials is not less than 0.15.
 2. A damperformulation which comprises the emulsion composition for vibrationdamping materials according to claim
 1. 3. The damper formulationaccording to claim 2, which comprises a polyvalent metal oxide. 4.Method of coating the damper formulation according to claim 2, whereinthe damper formulation is coated and dried in such a way that the drythickness of a coating is 1.5 to 5.0 mm.
 5. A vibration damping materialobtained by the method of coating according to claim
 4. 6. Method ofcoating the damper formulation according to claim 3, wherein the damperformulation is coated and dried in such a way that the dry thickness ofa coating is 1.5 to 5.0 mm.
 7. A vibration damping material obtained bythe method of coating according to claim 6.